Fix up and rename VisibleMargins() in preparation for making use of it.

ui/gfx/image/image_util_unittest.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/gfx/image/image_util.h"
 
 #include <vector>
 
 #include "base/memory/scoped_ptr.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "third_party/skia/include/core/SkRect.h"
 #include "ui/gfx/image/image_skia.h"
 #include "ui/gfx/image/image_unittest_util.h"
 
 TEST(ImageUtilTest, JPEGEncodeAndDecode) {
   gfx::Image original = gfx::test::CreateImage(100, 100);
 
   std::vector<unsigned char> encoded;
   ASSERT_TRUE(gfx::JPEG1xEncodedDataFromImage(original, 80, &encoded));
 
   gfx::Image decoded =
       gfx::ImageFrom1xJPEGEncodedData(&encoded.front(), encoded.size());
 
   // JPEG is lossy, so simply check that the image decoded successfully.
   EXPECT_FALSE(decoded.IsEmpty());
 }
 
-TEST(ImageUtilTest, TestVisibleMargins) {
-  // Image with non-transparent piece should return margins at those
-  // columns.
-  SkBitmap bitmap1;
-  bitmap1.allocN32Pixels(16, 16);
-  bitmap1.eraseColor(SK_ColorTRANSPARENT);
-  bitmap1.eraseArea(SkIRect::MakeLTRB(3, 3, 14, 14), SK_ColorYELLOW);
-  gfx::ImageSkia img = gfx::ImageSkia::CreateFrom1xBitmap(bitmap1);
-  int x = 0;
-  int y = 0;
-  gfx::VisibleMargins(img, &x, &y);
-  EXPECT_EQ(3, x);
-  EXPECT_EQ(13, y);
-  EXPECT_EQ(16, img.width());
+TEST(ImageUtilTest, GetVisibleMargins) {
+  int left, right;
 
-  // Full-width-transparent image should return margins in the center
-  // of the image.
-  SkBitmap bitmap2;
-  bitmap2.allocN32Pixels(16, 16);
-  bitmap2.eraseColor(SK_ColorTRANSPARENT);
-  gfx::ImageSkia img_transparent = gfx::ImageSkia::CreateFrom1xBitmap(bitmap2);
-  x = 0;
-  y = 0;
-  gfx::VisibleMargins(img_transparent, &x, &y);
-  EXPECT_EQ(8, x);
-  EXPECT_EQ(9, y);
-  EXPECT_EQ(16, img_transparent.width());
+  // Fully transparent image.
+  {
+    SkBitmap bitmap;
+    bitmap.allocN32Pixels(16, 16);

[danakj, 2016/03/25 23:35:28]

less symmetry would be nice, what if the code confused width and height
somewhere?

[Peter Kasting, 2016/03/26 01:01:57]

Sure, I can go through these and ensure that height/width calculations will
always give different results.

+    bitmap.eraseColor(SK_ColorTRANSPARENT);
+    gfx::ImageSkia img(gfx::ImageSkia::CreateFrom1xBitmap(bitmap));
+    gfx::GetVisibleMargins(img, &left, &right);
+    EXPECT_EQ(8, left);
+    EXPECT_EQ(8, right);
+  }
 
-  // Image with non-transparent piece that is skewed to one side should
-  // return margins at those columns.
-  SkBitmap bitmap3;
-  bitmap3.allocN32Pixels(16, 16);
-  bitmap3.eraseColor(SK_ColorTRANSPARENT);
-  bitmap3.eraseArea(SkIRect::MakeLTRB(3, 3, 5, 5), SK_ColorYELLOW);
-  gfx::ImageSkia img3 = gfx::ImageSkia::CreateFrom1xBitmap(bitmap3);
-  x = 0;
-  y = 0;
-  gfx::VisibleMargins(img3, &x, &y);
-  EXPECT_EQ(3, x);
-  EXPECT_EQ(4, y);
-  EXPECT_EQ(16, img3.width());
+  // Fully non-transparent image.
+  {
+    SkBitmap bitmap;
+    bitmap.allocN32Pixels(16, 16);
+    bitmap.eraseColor(SK_ColorYELLOW);
+    gfx::ImageSkia img(gfx::ImageSkia::CreateFrom1xBitmap(bitmap));
+    gfx::GetVisibleMargins(img, &left, &right);
+    EXPECT_EQ(0, left);
+    EXPECT_EQ(0, right);
+  }
 
-  // Image with non-transparent piece that is at one edge should
-  // return margins at those columns.
-  SkBitmap bitmap4;
-  bitmap4.allocN32Pixels(16, 16);
-  bitmap4.eraseColor(SK_ColorTRANSPARENT);
-  bitmap4.eraseArea(SkIRect::MakeLTRB(0, 3, 5, 5), SK_ColorYELLOW);
-  gfx::ImageSkia img4 = gfx::ImageSkia::CreateFrom1xBitmap(bitmap4);
-  x = 0;
-  y = 0;
-  gfx::VisibleMargins(img4, &x, &y);
-  EXPECT_EQ(0, x);
-  EXPECT_EQ(4, y);
-  EXPECT_EQ(16, img4.width());
+  // Image with non-transparent section in center.
+  {
+    SkBitmap bitmap;
+    bitmap.allocN32Pixels(16, 16);
+    bitmap.eraseColor(SK_ColorTRANSPARENT);
+    bitmap.eraseArea(SkIRect::MakeLTRB(3, 3, 13, 13), SK_ColorYELLOW);
+    gfx::ImageSkia img(gfx::ImageSkia::CreateFrom1xBitmap(bitmap));
+    gfx::GetVisibleMargins(img, &left, &right);
+    EXPECT_EQ(3, left);
+    EXPECT_EQ(3, right);
+  }
 
-  // Image with non-transparent piece that is at trailing edge should
-  // return margins at those columns.
-  SkBitmap bitmap5;
-  bitmap5.allocN32Pixels(16, 16);
-  bitmap5.eraseColor(SK_ColorTRANSPARENT);
-  bitmap5.eraseArea(SkIRect::MakeLTRB(4, 3, 16, 16), SK_ColorYELLOW);
-  gfx::ImageSkia img5 = gfx::ImageSkia::CreateFrom1xBitmap(bitmap5);
-  x = 0;
-  y = 0;
-  gfx::VisibleMargins(img5, &x, &y);
-  EXPECT_EQ(4, x);
-  EXPECT_EQ(15, y);
-  EXPECT_EQ(16, img5.width());
+  // Image with non-transparent section skewed to one side.
+  {
+    SkBitmap bitmap;
+    bitmap.allocN32Pixels(16, 16);
+    bitmap.eraseColor(SK_ColorTRANSPARENT);
+    bitmap.eraseArea(SkIRect::MakeLTRB(3, 3, 5, 5), SK_ColorYELLOW);
+    gfx::ImageSkia img(gfx::ImageSkia::CreateFrom1xBitmap(bitmap));
+    gfx::GetVisibleMargins(img, &left, &right);
+    EXPECT_EQ(3, left);
+    EXPECT_EQ(11, right);
+  }
+
+  // Image with non-transparent section at leading edge.
+  {
+    SkBitmap bitmap;
+    bitmap.allocN32Pixels(16, 16);
+    bitmap.eraseColor(SK_ColorTRANSPARENT);
+    bitmap.eraseArea(SkIRect::MakeLTRB(0, 3, 5, 5), SK_ColorYELLOW);
+    gfx::ImageSkia img(gfx::ImageSkia::CreateFrom1xBitmap(bitmap));
+    gfx::GetVisibleMargins(img, &left, &right);
+    EXPECT_EQ(0, left);
+    EXPECT_EQ(11, right);
+  }
+
+  // Image with non-transparent section at trailing edge.
+  {
+    SkBitmap bitmap;
+    bitmap.allocN32Pixels(16, 16);
+    bitmap.eraseColor(SK_ColorTRANSPARENT);
+    bitmap.eraseArea(SkIRect::MakeLTRB(4, 3, 16, 16), SK_ColorYELLOW);
+    gfx::ImageSkia img(gfx::ImageSkia::CreateFrom1xBitmap(bitmap));
+    gfx::GetVisibleMargins(img, &left, &right);
+    EXPECT_EQ(4, left);
+    EXPECT_EQ(0, right);
+  }
+
+  // Image with narrow non-transparent section.
+  {
+    SkBitmap bitmap;
+    bitmap.allocN32Pixels(16, 16);
+    bitmap.eraseColor(SK_ColorTRANSPARENT);
+    bitmap.eraseArea(SkIRect::MakeLTRB(8, 3, 9, 5), SK_ColorYELLOW);
+    gfx::ImageSkia img(gfx::ImageSkia::CreateFrom1xBitmap(bitmap));
+    gfx::GetVisibleMargins(img, &left, &right);
+    EXPECT_EQ(8, left);
+    EXPECT_EQ(7, right);
+  }
+
+  // Image with faint pixels.
+  {
+    SkBitmap bitmap;
+    bitmap.allocN32Pixels(16, 16);
+    bitmap.eraseColor(SkColorSetA(SK_ColorYELLOW, 0x02));
+    gfx::ImageSkia img(gfx::ImageSkia::CreateFrom1xBitmap(bitmap));
+    gfx::GetVisibleMargins(img, &left, &right);
+    EXPECT_EQ(8, left);
+    EXPECT_EQ(8, right);
+  }
+
+  // Fully transparent image with odd width.
+  {
+    SkBitmap bitmap;
+    bitmap.allocN32Pixels(17, 16);
+    bitmap.eraseColor(SK_ColorTRANSPARENT);
+    gfx::ImageSkia img(gfx::ImageSkia::CreateFrom1xBitmap(bitmap));
+    gfx::GetVisibleMargins(img, &left, &right);
+    EXPECT_EQ(9, left);
+    EXPECT_EQ(8, right);
+  }
 }